The funding bonds shall be issued by the board of directors at such time and manner and in such amounts as may be required to meet the demands of the district, as may be determined by the board of directors. The form, denomination, rate of interest, time, place and manner of payment and all matters relating to such issuance shall be determined by the board of directors, but the rate of interest shall not exceed 6 per cent per annum.
The funding bonds so issued may be sold in such amounts and at such times and in such manner as the board of directors may determine, or they may be delivered to any contractor performing any work for the
district, at par, in satisfaction of any sum due upon his contract.